Heart rate variability and plasma nephrines in the evaluation of heat acclimatisation status.

PURPOSE: Heat adaptation (HA) is critical to performance and health in a hot environment. Transition from short-term heat acclimatisation (STHA) to long-term heat acclimatisation (LTHA) is characterised by decreased autonomic disturbance and increased protection from thermal injury. A standard heat tolerance test (HTT) is recommended for validating exercise performance status, but any role in distinguishing STHA from LTHA is unreported. The aims of this study were to (1) define performance status by serial HTT during structured natural HA, (2) evaluate surrogate markers of autonomic activation, including heart rate variability (HRV), in relation to HA status. METHODS: Participants (n = 13) were assessed by HTT (60-min block-stepping, 50% VO2peak) during STHA (Day 2, 6 and 9) and LTHA (Day 23). Core temperature (Tc) and heart rate (HR) were measured every 5 min. Sampling for HRV indices (RMSSD, LF:HF) and sympathoadrenal blood measures (cortisol, nephrines) was undertaken before and after (POST) each HTT. RESULTS: Significant (P < 0.05) interactions existed for Tc, logLF:HF, cortisol and nephrines (two-way ANOVA; HTT by Day). Relative to LTHA, POST results differed significantly for Tc (Day 2, 6 and 9), HR (Day 2), logRMSSD (Day 2 and Day 6), logLF:HF (Day 2 and Day 6), cortisol (Day 2) and nephrines (Day 2 and Day 9). POST differences in HRV (Day 6 vs. 23) were + 9.9% (logRMSSD) and - 18.6% (logLF:HF). CONCLUSIONS: Early reductions in HR and cortisol characterised STHA, whereas LTHA showed diminished excitability by Tc, HRV and nephrine measures. Measurement of HRV may have potential to aid real-time assessment of readiness for activity in the heat.

The British Services Dhaulagiri Medical Research Expedition 2016: a unique military and civilian research collaboration.

INTRODUCTION: High-altitude environments lead to a significant physiological challenge and disease processes which can be life threatening; operational effectiveness at high altitude can be severely compromised. The UK military research is investigating ways of mitigating the physiological effects of high altitude. METHODS: The British Service Dhaulagiri Research Expedition took place from March to May 2016, and the military personnel were invited to consent to a variety of study protocols investigating adaptation to high altitudes and diagnosis of high-altitude illness. The studies took place in remote and austere environments at altitudes of up to 7500 m. RESULTS: This paper gives an overview of the individual research protocols investigated, the execution of the expedition and the challenges involved. 129 servicemen and women were involved at altitudes of up to 7500 m; 8 research protocols were investigated. CONCLUSIONS: The outputs from these studies will help to individualise the acclimatisation process and inform strategies for pre-acclimatisation should troops ever need to deploy at high altitude at short notice.

Copeptin and arginine vasopressin at high altitude: relationship to plasma osmolality and perceived exertion.

PURPOSE: A diuresis is a key part of acclimatisation to high altitude (HA). Arginine vasopressin (AVP) is a hormone involved in salt and water balance and may potentially have a role in the development of altitude illness. ProAVP (copeptin) is more stable than AVP and is assayed by a straightforward, automated method. We investigated the relationship of AVP to copeptin and the copeptin response to exercise and altitude illness in a large cohort during a field study at HA. METHODS: 48 subjects took part in a 10-day trek at HA. Venous blood samples were taken at 3,833, 4,450 and 5,129 m post-trek (exercise) and the following day at rest. Daily recordings of symptoms of altitude illness, oxygen saturations and perceived exertion were carried out. RESULTS: AVP and copeptin levels increased with exercise and correlated closely (ρ 0.621 p < 0.001), this was strongest in the stressed state when AVP secretion was highest, at 5,129 m post-exercise (ρ 0.834 p < 0.001). On two-way ANOVA, both altitude (F = 3.5; p = 0.015) and exercise (F = 10.2; p = 0.002) influenced copeptin levels (interaction F = 2.2; p = 0.08). AVP levels were influenced by exercise (F = 14.4; p = 0.0002) but not altitude (F = 2.0; p = 0.12) with no overall group interactions (F = 1.92.6; p = 0.06). There was no association between copeptin or arginine vasopressin and altitude illness. Copeptin correlated with the Borg RPE score and was significantly higher in the group with a Borg score ≥15 (7.9 vs. 3.7 p < 0.001). CONCLUSION: We have shown that arginine vasopressin and copeptin levels correlate and are suppressed below 5,129 m. Furthermore, we have demonstrated that exertion, rather than altitude illness or increasing osmolality, is the stimulus for increases in copeptin.

The Hearts of Heroes: the epidemiology of cardiac disease in the UK Armed Forces.

When the general public look from the outside at the armed services, their impression is often one of earnest young men and women who are the pinnacle of physical fitness and health, and put their lives on the line for their country. There is usually sadness and respect for those killed on active operations, having put themselves in harm's way. Therefore, when the public discover that more than 1 in 10 deaths in the UK Armed Forces are due to cardiovascular disease, the air of sadness is invariably replaced with surprise and disbelief. These figures, while lower than those due to deaths in accidents, are approaching the numbers of those due to suicide in the armed services; yet deaths from cardiac disease are barely recognised by society, in spite of many of them being avoidable. This article reviews the epidemiology of cardiac disease in the UK Armed Forces, both in terms of morbidity and mortality. It outlines current understanding and gaps in the knowledge regarding the burden of cardiovascular disease in the military population. The particular demographics of the Armed Forces and its influence on cardiac disease burden are discussed. The role of inherited and congenital diseases in younger servicemen and women is highlighted, as is the trend that with increasing age, the burden of disease shifts to ischaemic heart disease, which becomes the dominant cause of both death and disability.

Managing the military patient with syncope.

Syncope is a relatively common occurrence in military populations. It is defined as a transient loss of consciousness due to global cerebral hypoperfusion, characterised by a rapid onset, short duration and a spontaneous and complete recovery. While the symptom of syncope is easily elicited, discovering the mechanism can be more problematic and may require a plethora of diagnostic tests. The aim of this paper is to review current evidence pertaining to the classification, investigation and management of syncope, from a military perspective. Emphasis is placed on assisting primary healthcare professionals in the assessment and management of syncope, in the UK and on operations, while providing explicit guidance on risk. The occupational limitations required in safely managing patients with syncope are stressed along with the potential long-term limitations.

Cardiomyopathies and the Armed Forces.

Cardiomyopathies are a group of heterogeneous myocardial diseases that are frequently inherited and are a recognised cause of premature sudden cardiac death in young individuals. Incomplete expressions of disease and the overlap with the physiological cardiac manifestations of regular intensive exercise create diagnostic challenges in young athletes and military recruits. Early identification is important because sudden death in the absence of prodromal symptoms is a common presentation, and there are several therapeutic strategies to minimise this risk. This paper examines the classification and clinical features of cardiomyopathies with specific reference to a military population and provides a detailed account of the optimum strategy for diagnosis, indications for specialist referral and specific guidance on the occupational significance of cardiomyopathy. A 27-year-old Lance Corporal Signaller presents to his Regimental medical officer (RMO) after feeling 'light-headed' following an 8 mile unloaded run. While waiting to see the RMO, the medical sergeant records a 12-lead ECG. The ECG is reviewed by the RMO immediately prior to the consultation and shows voltage criteria for left ventricular (LV) hypertrophy and inverted T-waves in II, III, aVF and V1-V3 (Figure 1). This Lance Corporal is a unit physical training instructor and engages in >10 h of aerobic exercise per week. He is a non-smoker and does not have any significant medical history.

Screening for cardiac disease in potential recruits to the British Army.

The British Army screens potential recruits for disease, including cardiovascular disease, at the pre-employment medical assessment in the Army Selection Centres. The epidemiology of cardiovascular disease in the Armed Forces coupled with the high physical demand placed on the cardiovascular system, often in remote locations make screening desirable. This is particularly pertinent as servicemen and women die from cardiovascular disease each year. To evaluate this particular screening system it is essential to understand the aim of the system, how it is designed and how screening systems in general are evaluated. The efficacy of a screening test is quantified using the measurements of sensitivity, specificity and likelihood ratios. These measurements are defined and the pitfalls associated with evaluating a screening system are described. The different screening tests used to identify cardiac disease and their individual strengths and weaknesses, are illustrated. Finally the article reviews the previous British Army recruit cardiac screening system, that used a stereotyped history and physical examination and the newer system that replaced it, which includes the incorporation of the 12-lead ECG and on site echocardiography in individuals revealing abnormalities on history, examination or ECG.

Myocarditis and the military patient.

Myocarditis, simply defined as inflammation of the heart muscle, is a commonly encountered cardiac disease in primary and secondary care, both in the UK and on Operational deployments. In the UK Armed Forces, myocarditis results in deaths as well as the premature termination of military careers on medical grounds. The aetiology is usually the result of a number of infectious aetiologies with viruses being the most common pathogens in the vast majority of cases. However, it may also be the result of autoimmune activation, chemical or pharmacological toxins, environmental insult or hypersensitivity reactions. Particular aetiologies that are more likely to be seen in a military population are discussed and include certain infections, smallpox vaccine, and hyperthermia and hypothermia. The clinical features can be highly variable ranging from an asymptomatic infection to fulminant heart failure. Features pertinent to the military doctor, including the natural history, investigative modalities and management strategies, with a particular emphasis on the occupational impact of myocarditis in the UK Armed Forces are reviewed.

Pericarditis and pericardial effusions in the military patient.

The pericardium is the thin double-walled sac encapsulating the heart which has a number of important physiological roles including fixing the heart in the mediastinum, protecting it from cross-organ infection (eg, lung) and lubricating cardiac contraction. The pericardium is associated with several disease syndromes that occasionally affect the military population. These include acute and recurrent pericarditis, pericardial effusion and tamponade, which may result from a large number of different aetiological agents. Pericardial diseases have a wide range of clinical manifestations and the diagnosis of pericardial diseases can be a challenge. This article reviews the anatomy and pathophysiology of pericarditis and pericardial effusions before outlining their clinical features, recommended investigations and management options. Particular emphasis is placed on the impact of these diseases for patients in a military occupational environment.

[Recreational athletes and doping--a survey in 11 gyms in the area of Frankfurt/Main]. / Doping bei Freizeitsportlern--Eine Untersuchung in 11 Fitnessstudios im Raum Frankfurt am Main.

BACKGROUND: Doping no longer concerns exclusively competitive sports, but also recreational sports. METHOD: Survey of 484 recreational athletes in 11 gyms in the area of Frankfurt/Main. RESULTS: 12.9% of the men and 3.6% of the women reported to take anabolic drugs. Theyconsumed anabolic steroids (100%; 35% p.o., 71% parenterally), stimulants (14%) and growth hormone (5%). Suppliers were friends (39%), sports mates (28%), physicians (28%) and coaches (6%). The acquisition costs amounted to an average intake over 9 weeks to 175 Euro. Information about doping side effects came from literature (67%), physicians (38%), sports mates and the so-called Black Book (14% respectively), coaches, friends and Internet (5% respectively). 2% of the athletes with abuse of doping substances were smokers, 11% had a drink several times a week, 3% also consumed other drugs, 35% had consumed other drugs in the past. Abusers of doping substances primarily intended to increase muscle size (86%) and strength (61%). CONCLUSION: From a sports medical point of view it is concerning that the proportion of doping drugs prescribed by physicians has doubled in the decade after the publication of the predecessor study in Northern Germany despite optimized sports medical and legal education measures.

Relationship between combat-related traumatic injury and ultrashort term heart rate variability in a UK military cohort: findings from the ADVANCE study.

INTRODUCTION: Combat-related traumatic injury (CRTI) has been linked to an increased cardiovascular disease (CVD) risk. The long-term impact of CRTI on heart rate variability (HRV)-a robust CVD risk marker-has not been explored. This study investigated the relationship between CRTI, the mechanism of injury and injury severity on HRV. METHODS: This was an analysis of baseline data from the ArmeD SerVices TrAuma and RehabilitatioN OutComE (ADVANCE) prospective cohort study. The sample consisted of UK servicemen with CRTI sustained during deployment (Afghanistan, 2003-2014) and an uninjured comparison group who were frequency matched to the injured group based on age, rank, deployment period and role in theatre. Root mean square of successive differences (RMSSD) was measured as a measure of ultrashort term HRV via <16 s continuous recording of the femoral arterial pulse waveform signal (Vicorder). Other measures included injury severity (New Injury Severity Scores (NISS)) and injury mechanism. RESULTS: Overall, 862 participants aged 33.9±5.4 years were included, of whom 428 (49.6%) were injured and 434 (50.3%) were uninjured. The mean time from injury/deployment to assessment was 7.91±2.05 years. The median (IQR) NISS for those injured was 12 (6-27) with blast being the predominant injury mechanism (76.8%). The median (IQR) RMSSD was significantly lower in the injured versus the uninjured (39.47 ms (27.77-59.77) vs 46.22 ms (31.14-67.84), p<0.001). Using multiple linear regression (adjusting for age, rank, ethnicity and time from injury), geometric mean ratio (GMR) was reported. CRTI was associated with a 13% lower RMSSD versus the uninjured group (GMR 0.87, 95% CI 0.80-0.94, p<0.001). A higher injury severity (NISS ≥25) (GMR 0.78, 95% CI 0.69-0.89, p<0.001) and blast injury (GMR 0.86, 95% CI 0.79-0.93, p<0.001) were also independently associated with lower RMSSD. CONCLUSION: These results suggest an inverse association between CRTI, higher severity and blast injury with HRV. Longitudinal studies and examination of potential mediating factors in this CRTI-HRV relationship are needed.

Cardiac arrhythmias at high altitude.

Palpitations at high altitude have been experienced, but seldom recorded, for centuries. The hypoxia, sympathetic activation and alkalosis of altitude predispose to cardiac ischaemia and arrhythmia. Indeed, sudden cardiac death is responsible for 30% of all deaths during mountain sports at altitude. This article reviews the literature to date on the evidence for cardiac arrhythmias at altitude.

The use of exercise and dietary supplements among British soldiers in Afghanistan.

BACKGROUND AND OBJECTIVES: Recently published case reports, coupled with a large observational study of 1017 deployed servicemen to Iraq (January 2009), has highlighted the issue and potential concerns regarding the unregulated use of dietary and exercise supplements within the British military. Consequently, an exploratory pilot study was undertaken to assess whether the findings of the previous Iraq study were applicable to current deployed British servicemen in Afghanistan. METHODS: This was a voluntary questionnaire-based study targeted at individuals attending a health promotion fair in Camp Bastion, Afghanistan in June 2010. RESULTS: From 150 questionnaires handed out there were 87 completed questionnaires (58% return). The mean age was 28.0 (SD 7.1; range of 18-50 years) with 89.7% being male. From the total of 87 persons 46.0% were self-declared current smokers with 37.9% admitting to drinking >6 caffeinated drinks per day. Forty nine persons (56.3%) admitted to a history of supplement use with 35 (40.2% compared with 32.0% in 2009 in Iraq) declaring current use. The average duration of supplement use among current users was 3.0 (2.0-9.0) months. The main sources of supplement supply were via local NAAFI purchase (57.1%), internet purchase (40.0%) and via their local chemist (2.9%). The main types of supplement used were proteins/amino acids (85.7%), creatine (34.3%), chromium (31.4%), stimulants (17.1%), hydroxycut (5.7%), and testosterone boosters (1.2%) with no persons admitting to the use of ephedra or anabolic steroids. CONCLUSIONS: A significant proportion of the British servicemen employed on operations in Afghanistan who were sampled, admitted to current dietary and exercise supplement use whilst on deployment. The results of this small study suggest that their use on operations may be increasing. Smoking rates and caffeine consumption, on deployment, remain high in the British military. A larger detailed study with greater representation among soldiers deployed to forward operating bases would be helpful to fully appreciate the scale of supplement use.

Cardiology.

Cardiac disease remains a significant threat to both local and deployed military populations. In this article we present several cardiac case reports which may be of educational use to the military clinician.

Dietary supplements and military operations: caution is advised.

We describe the case of a 32-year-old soldier who presented with acute organic psychosis during an operational tour to Iraq. This was precipitated by excessive consumption of caffeine coupled with additional use of oral nutritional stimulants. Her biochemical profile was compounded by the additional use of exogenous creatine. We present a brief overview of the issue of exercise supplementation and highlight some of the potential problems and clinical issues surrounding their use. This has important implications for both serving soldiers and the wider medical community.

Back pain in a Bangladeshi worker in Iraq.

Pyogenic Spinal Infection (PSI) is an uncommon disorder encompassing a broad spectrum of diseases including septic spondylodiscitis, osteomyelitis, epidural and paravertebral abscess formation. Presentation can be vague and highly variable but usually includes back pain and fever. Whilst predisposing factors, such as trauma and diabetes can often be identified a pathogenic organism may not be identified in up to a half of all cases leading to significant delay in both accurate diagnosis and effective treatment. Precise spinal imaging is essential and includes plain X-ray, CT and preferably MRI. The treatment of PSI can be conservative (including antibiotics); however, spinal surgery may be required for the complications in up to 50% of cases, with varying degrees of success. We present a challenging case of PSI encountered in a locally-employed 42-year-old Bangladeshi civilian working in Iraq. Despite obvious resource limitations available within a Role 2 Field Hospital, clinical suspicion coupled with repeat spinal CT was pivotal in obtaining the diagnosis. The patient was repatriated to Bangladesh for MRI and definitive surgical treatment.

Self-administration of exercise and dietary supplements in deployed British military personnel during Operation TELIC 13.

OBJECTIVES: Recent operational experience has led to the identification of several potentially serious adverse events related to the use of dietary and exercise supplements among British Army personnel. This study aimed to establish the point prevalence of dietary and exercise supplement usage in British soldiers on Op TELIC during January 2009. METHODS: A cross-sectional questionnaire-based study of British military personnel located at the Contingency Operating Base (COB), in Basra, was performed during the sixth week of Op TELIC 13. RESULTS: From 1544 questionnaires (target population) issued, a total of 1017 (65.9%) completed questionnaires were evaluated. The mean population age was 29.5 years (range 18-58) of which 87.4% were male. 417/1017 persons (41.0%) admitted to a history of supplement use of which 32.0% were current users and 9.4% were previous users. Of these current users, 66.0% started taking them on their current deployment. The most commonly taken supplements were whey protein (18.8%), amino acids (17.9%), and creatine (13.2%). There were 14 persons (1.4%) who admitted to current use of anabolic steroids. The most-frequently given reasons for taking supplements were either to 'increase muscle bulk' (40.4%) or to aid training and recovery (20.8%). CONCLUSIONS: This is the first study to investigate the use of exogenous nutritional supplements within the British Military and has identified their widespread use during operational deployment. The use of anabolic steroids is particularly worrying, given both their illegality and their well-recognised and deleterious health effects. There is a need for greater awareness and education regarding potential benefits and dangers of supplement use in order to maximise any potential benefits and minimise clinical risk.

Antithrombotic treatment in atrial fibrillation.

Atrial fibrillation (AF) can significantly increase morbidity and mortality. It is gaining in clinical and economic importance, being the most commonly encountered tachyarrhythmia in clinical practice. Stroke is the most serious complication. Evidence from AF antithrombotic treatment trials is reviewed, risk stratification of patients with AF is discussed, and recommendations for anticoagulation are presented.

An unusual case of misdiagnosed ventricular tachycardia.

We present the case of a 71-year-old man, with known Parkinson's disease and previous coronary artery bypass surgery, who presented with acute chest pain. His initial 12 lead electrocardiogram (ECG) was unremarkable; however, a repeat 12 lead ECG during further chest pain suggested a ventricular tachycardia (VT) for which he was commenced on an intravenous amiodarone infusion. However, later analysis of his ECGs revealed that the apparent VT was, in fact, an artefact related to his parkinsonian tremor.

[Histopathologic diagnosis of infectious loosening of joint prostheses]. / Histopathologische Diagnostik der infektiösen Gelenkendoprothesenlockerung.

To optimize the reliability of histopathological criteria for periprosthetic infection, 110 tissue specimens from joint prostheses were analyzed with quantification of the inflammatory cells and immunohistochemical typing of lymphocytes and plasma cells. As reported in the literature the density of granulocytic infiltration was the most sensitive marker of periprosthetic infection with an accuracy of 84%, a sensitivity of 91%, a specificity of 81%, a positive predictive value of 67%, and a negative predictive value of 95%, using the mostly favored limit value of 5 granulocytes per HPF. T lymphocytes were also found to a high degree in cases of aseptic loosening. In contrast, B lymphocytes were predominantly seen in cases with periprosthetic infection. For B lymphocytes an accuracy of 80% and a sensitivity of 79% were calculated and for plasma cells an accuracy of 75% and a sensitivity of 79%. Our data suggest that the quantification of granulocyte, B-cell, and plasma cell infiltrates is an important parameter for verifying the diagnosis of periprosthetic infection.